If yu watned to increase yoir muscle endurance, it would be important to participate on activities that

You would need to participate in activities that are harder than what you normally do, something that will test how hard you can work. 

It would be important to participate in activities that spread your boundaries and are varied. You can for example swim, run, or play basketball. This strengthens your legs, arms, and upper body strength. You should do things that require a lot of effort, and get you tired easily. This will expand your endurance when doing these activities. This over time will build up your core and self esteem. You also have to have the mental stamina that you can do it. Have confidence that you will succeed and anything is possible. When you can't do something, it's important to have a mind set that you can do it.

Icannot see any engraving so i cant answer 12.massacre means wholesale slaughter and thats what happend when they the boston citizens